Tomales Bay is on the 303(d) list for Impaired Water Bodies for sediment/ siltation, nutrients, and mercury, and the Petaluma River is on the 303(d) list for sediment/siltation, nutrients, and pathogens. The Aquatic Science Center has been hired by the San Francisco Bay Regional Water Quality Control Board (SFBRWQCB) to assist with the scientific basis of Total Maximum Daily Load (TMDL) projects to resolve these water quality impairments. The project will investigate the possibility of impairment and provide technical analysis in support of the SFBRWQCB’s efforts to improve water quality and protect beneficial uses for humans and wildlife. For Tomales Bay, the focus of the project will be on mercury since previous studies have indicated that high concentrations of mercury in fish and benthic organisms threaten the health of numerous wildlife species that are found within the Bay's diverse habitats. There will be a significant field component to collect new data in order to characterize current concentrations of mercury in sediment, water and small prey fish consumed by piscivorous wildlife, which are most at risk for mercury toxicity. In addition, the ASC will complete an evaluation of numeric targets for the three target pollutants and a conceptual model/impairment assessment to characterize the magnitude and nature of sources of pollutants, and linkage to impacts on beneficial uses. For the Petaluma River, where there is less data available to indicate the status of impairment, the ASC completed a preliminary impairment assessment based on existing data, and will work with the SFBRWQCB to further define the technical support needed for the project.

Project Funder

State Water Resources Control Board (SWRCB)

Tomales Petaluma
-Impairment Assessment for Mercury -Monitoring Plan
-Data -Preliminary Impairment Assessment
Programs and Focus Areas: 
Clean Water Program
Location Information